Servo-controls



Jan. 2, 1962 J. FAISANDIER 3,015,313

SERVO-CONTROLS Filed Jan. 11, 1957 4 Sheets-Sheet 1 FIG.\

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' Jan. 2, 1962 .J. FAISANDIER SERVO-CONTROLS 4 Sheets-Sheet 2 Filed Jan. 11, 1957 FIG.3

Jan. 2, 1962 4 Sheets-Sheet 55 Filed Jan. .11, 1957 Fig.5

Jan. 2, 1962 J. FAISANDIER 3,015,313

SERVO-CONTROLS Filed Jan. 11, 1957 4 Sheets-Sheet 4 3,015,313 SERVO-CONTROLS Hacques Faisandier, 32 Blvd. Felix-Fame, Chatillon-sous-Bagneux, France Filed Jan. 11, 1957, Ser. No. 633,718 Claims priority, application France Jan. 18, 1956 6 Ciaims. (Cl. 121-41) The invention relates to servo-controls, especially for the automatic piloting of aeroplanes, airships, teleguided machines and applications of the same order.

An object of the invention is to obtain a servo-control, the time of response of which is extremely short, that is, of the order of a few milliseconds, and which will be applicable every time a problem of this kind arises.

With this object in view, the jack of the servo-control is fed by a principal distributor, preferably of the kind with a rotatable slide valve. This distributor is controlled by a small low-pressure auxiliary jack which is itself fed by an auxiliary distributor, preferably of the kind with a rotatable slide valve, which is, in turn, controlled by an electric movable frame with a very small time constant.

Another object of the invention is to obtain a servocontrol, the final position of which is defined by an input voltage.

With these objects in view, the frame of the servocontrol according to the invention is controlled by an electronic amplifier which receives:

(a) An input voltage that is a control-signal function;

(b) An output voltage which fixes the output movement;

(c) Damping voltages, especially voltages which fix the movement of the frame and the movement of the auxiliary jack respectively, that is to say which fix the acceleration and the speed of the output movement respectively.

Another and auxiliary object of the invention is a combination which renders it possible to operate selectively either by means of the electrical connection, which constitutes the first object of the invention, or by the usual linkage, suitably modified for this purpose.

Another auxiliary object of the invention is a device which renders it possible to give a lead to the electrical controlling signal in relation to the output signal, which may be advisable in certain circumstances of flight or of firing.

With the first auxiliary object in view, the control stick controls a potentiometer and also controls the linkage through the intermediary of an optional interlocking device which enables the linkage to follow the output movement without it being possible for this movement to interfere mechanically with that of the control stick when the latter controls solely the electrical connection.

With the second auxiliary object in view, the invention provides, in the circuit for transmitting the input signal, an electrical device which renders it possible to introduce a time factor into the transmission of the signal.

One of the objects of the present invention is to render possible, in a simple manner, the reciprocal testing of the electric and hydraulic circuits.

Another object of the present invention is to render possible the separate testing of each of the hydraulic supply circuits and of each of the hydraulic circuits which correspond to the duplication of the hydraulic servocontrol proper.

tates Patent In the accompanying drawings:

FIG. 1 is a diagrammatic section cording to the invention.

FIG. 2 is a diagram of the electrical connections.

FIG. 3 is the diagram of the electrical connections in the case of the combination with the usual linkage.

FIG. 4 is a diagrammatic representation of the mechanical connection.

FIG. 5 represents diagrammatically the duplication of the hydraulic circuits and the testing device; and

FIG. 6 represents the diagram for the duplication of the electric circuits.

In FIG. 1, the reference numeral 1 denotes the body of the jack which is to be controlled electrically. 2 denotes the rod by means of which the jack exerts its action, for example on the linkage to an aeroplane-control surface (not shown).

The rod 2 carries the piston 3, on each of the faces of which high pressure, for example 200 kg./cm. can be caused to act, which pressure arrives from the source of pressure (not shown) through the pipe 4, while the return to the reservoir takes place through the pipe 5. 6 denotes the principal distributor which is here a conventional distributor of the rotatable type which is adapted, in the usual and known manner, to put into communication selectively either the high pressure or the return to the reservoir with one of the pipes 7 and '8 which connect the distributor to the ends of the cylinder of the jack. The displacement of the principal distributor 6 is controlled by the rod 9 of the auxiliary jack 1%, this rod acting through the-intermediary of hinged links 11 and 12. The jack 10 is controlled by the aum'liary distributor 41 which is also a conventional distributor of the rotatable slide-valve type and which renders it possible to put the low pressure, for example 15 kg./cm. which arrives from a source of pressure (not shown) through the pipe 42, selectively into communication with one of the pipes 13 and 14 which cause this pressure to arrive either on to one face or the other of the piston 15 of the jack 10. The distributor also enables one of the pipes 13 and 14 to be put selectively into communication with the reservoir through the pipe 16.

The control of the rotary valve distributor 17 of the jack 10 is effected by the movable frame 18, the axle 19 of which operates the lever 20 which, by means of a lug 21, acts on the lever 22 which is keyed on the axle 23 of the rotary valve distributor 17.

The movable frame 18 is displaced in the gap of a magnetic circuit 24, the core of which is seen at 25. 26 denotes the terminal through which the voltage arrives at the said movable frame. In FIG. 1, 27 denotes the amplifier at which the input voltage arrives through 28.

This input voltage may of the control acbe supplied in any known manner either by manual control or by an automatic piloting device. The rod 2 carries the wiper of a potentiometer 29, the voltage of which, that fixes the output movement, arrives into the amplifier 27 through 30. The link 12 also carries the wiper of a potentiometer 31, the voltage of which, that fixes the speed of the output movement, arrives at the amplifier 27 through 32.

The lever 2i) carries the wiper of the potentiometer 34, the voltage of which fixes the speed of the angular rotation of the shaft 19, hence denotes the acceleration of the output movement of piston rod 2. The voltage arrives at the amplifier 27 through 33. 'The resultant which is about voltage leaves the amplifier at 40 and arrives at the contact 26.

In the diagram shown in FIG. 2, there is given a more detailed example of the electrical connection of the amplifier 27. In this figure, the inputs 28, 30, 32 and 33 of FIG. 1 have been represented. Consequently, the input voltage E arrives through 28, the output voltage S arrives through 30, a voltage, the principal term of which is dt that is proportional to the speed of the rod 2 of the principal jack, arrives through '32, and a voltage, the principal term of which is (1118 M 8 E+ S 'W 0 represents a damped circuit.

If desired, the constant speed lag may be eliminated by a fifth input 36 on which a voltage adE' dt is impressed, or the input 36 may be replaced by the condenser 37 which is connected in parallel with an impedance of the circuit 28.

It is also possible to cause an auxiliary voltage, given by the transformer 39, which imposes slight vibrations on the movable 'frame in order to eliminate the efiect of static friction to arrive at the point 38. This expedient is known per se and may be replaced by equivalent electrical or mechanical expedients which are also well known to technicians.

The operation is as follows:

The voltage at the output 40 of the amplifier produces a deflection of the movable frame, the displacement of which is of the order of 30 to one side or the other of its mean position. This movement is transmitted to the rotary valve distributor 17, the angular displacement of in relation to its neutral position. The rotation of the rotary valve distributor 17 in one particular direction sends low'pressure, which is, for example kg./cm. on to the corresponding face of the piston of the jack 10, and the corresponding displacement of the jack 10 causes the slide valve of the distributor 6 to rotate in the corresponding direction; the distributor 6, in turn, sends high pressure, for example a pressure of the order of 200 kg./cm. on to the corresponding face of the piston 3. p The resultant movement of the rod 2 gives a voltage S which serves to fix the output movement; this voltage is received by the amplifier through conductor 30. The displacement of the rod 12 and-of the lever has also produced through the potentiometers 31 and 34, respectively, the appearance of corresponding voltages and 2 3 at 32 and 33 The set of voltages, which arrive through the imputs ble frame, 18,, as has hereinbefore been stated.

In FIG. 3, the control stick 261, which has been restored to the neutral position by the spring 202 which. rests, at 203, on a fixed point of the fuselage, directly controls the potentiometer 204 which supplies, into the circuit 128, a voltage which is proportional to its angular displacement.

Placed in the circuit 128 is the switch 205, which enables the control by the control stick to be eliminated when the automatic pilot is connected.

In parallel with an impedance of the circuit 128 is the condenser 137 which can be connected or disconnected at the will of the pilot by the switch 2% and the object of which is to give the control signal a lead.

It is pointed out that, in this application, the condenser 137 has a purpose which is slightly different from that of the condenser 37. In the foregoing case through phase shifting it gives a systematic lead Whereas, in the example shown in FIG. 2, it was used for eliminating the constant-speed lag. Located on the linkage 102 of the control surface 207 is a potentiometer 129 which supplies, into the circuit 130, a voltage which is proportional to its displacement. The voltages corresponding to potentiometers 128 and 129 are sent to the amplifier 127 which also receives, through the circuit 208, auxiliary voltages coming, through the intermediary of the switch 209, from the automatic pilot 210, or from the yaw stabiliser 211, or from the corrector of Zero as a func tion of the Mach number, or from any other auxiliary signal 212. If the resultant voltage at the input of the amplifier 127 is not Zero, the resultant voltage amplified by the amplifier causes the movable frame 118 and the auxiliary distributor 141, which controls the auxiliary jack 110, to rotate. The latter drives the principal dis tributor 106 which controls the principal jack 101 of the control surfaces; this varies the voltage given by the potentiometer 129 until the resultant voltage at the input of the amplifier 127 is zero. There is represented, at 213, a second winding of the movable frame which acts, through the intermediary of the correcting network 214, to give a damping voltage through 233.

FIG. 4 represents, more especially, the interlocking connection of the control stick. In this figure, the control stick 201 is shown and the potentiometer 204 is indicated by way of reminder. The joy-stick acts upon the linkage 215 which may or may not be fixed to the linkage 102 of the control surface 207.

The mechanical interlocking of the rods 102 and 215 is effected with the aid of the device 216 which is integral with the rod 102 and in which the rod 215 can slide. The rod 215 carries a diabolo 217 which can be stopped by the detent 218 of the electromagnet 219.

When the electromagnet 219 is energised, the rods 102 and 215 are completely interlocked. The control is then manual.

If the electromagnet 219 is de-energised, the rods 162 and 215 are no longer mechanically interlocked, the rod 215 follows the input movement and the rod 102 follows the output movement, these two movements being, in principle, identical, that is to say the arrangement of the apparatus being chosen so that these movements are equal. In practice, the diabolo 217 renders possible a clearance of the order of 5% more or less in order that the input movements and the output movements should not react on one another otherwise than hydraulically to prevent direct interference of the movement of rod 215 on rod 102.

In FIGS. 5 and 6, P and P denote the upstream ends of the servo-control of the two hydraulic supply circuits which are not shown in detail. The return routes B and B to the reservoir correspond to these circuits respectively. On the circuits P and P are electric plugs 301 and 302 respectively, which are represented very diagrammatically.

Inserted downstream of the electric plugs 301 and 362 is a selecting device 393, such as that described in the specification of Patent No. 2,868,217, which is incorporated herein by reference, which allows the automatic passage of the circuit P to the circuit P in the case of failure of the pressure in P The selecting device 363 may be replaced by any equivalent device which renders possible the automatic passage or the semi-automatic passage or a controlled passage from one circuit to the other, these devices not being described herein as they are already known.

Downstream of the device 303 are two auxiliary distributors 304 and 305 which control the auxiliary jacks 306 and 307 respectively that are connected in series to the crank 308 which controls the principal distributor 369 of the principal jack 310.

In this case, the distributors 396 and 307 are independent of each other and control the distributors 363 and 369 (the latter not shown) respectively which can control the jack 310 or the jacks 310 and 310' (the latter not shown) respectively, which are connected in series to the control surface 311.

The distributor 334- is fed through the conduit 312, 313, 314 in which the electric plug 315 is inserted. The distributor 335 is fed through the conduit 312, 316, 317, 318, in which an electromagnet 319 is inserted. The distributor 364, which feeds the two chambers of the jack 3% alternately through the conduits 321) and 321, can be short-circuited by means of the conduit 322, the unidirectional valve 323 and the conduits 324 and 325.

When the pressure ceases to be exerted through the conduit 322 on the head of the spring valve 323, the latter opens under the action of its spring, and the two chambers of the jack 336 are subjected to the same pressure; this puts the jack 3% out of action if it is independent or enables it to follow the movements imposed by the jack 337 if the two jacks are connected together.

The same by-pass device is used for the distributor 305 and will not be described again.

It follows from the foregoing description that The closing of the plug 301 enables the automatic substitution of P for P to be checked;

The closing of the plug 392 enables the efiective operation of P to be checked;

The closing of the plug 315 enables one to check that the hydraulic circuit of the jack 307 is operating and that the electric circuit which controls the distributor 305 is operating; and

The closing of the plug 319 enables one to check that the hydraulic circuit of the jack 366 is operating and that the electric circuit which controls the distributor 304 is operating.

The said electric circuits have been represented in the diagram of the connections of FIG. 6.

The control stick 321, that is returned to its neutral position by the spring 322 which rests, at 323, on a fixed point of the fuselage, directly controls the potentiometers 324 and 325 which supply, into the circuits 326 and 327, voltages which are proportional to its angular displacement.

In these circuits are switches 344 and 345 which render it possible for the control to be eliminated by the control stick when the automatic pilot is connected or to test each of the circuits 326 and 327.

Located in the linkage 328 of the control surface 311 are potentiometers 329 and 330 which supply, into the circuits 331 and 332, voltages which are proportional to its displacement.

The resultant voltages of the circuits 326, 331, on the one hand, and of the circuits 327 and 332, on the other, are sent into the amplifiers 334 and 333 respectively.

The auxiliary voltages coming, through switch 337, from the automatic pilot 338, or from the yaw stabiliser 339 or from the zero corrector to a function of the Mach number or from any other auxiliary signal or mixture of auxiliary signals, are also sent to the amplifiers 333 and 334 respectively.

The ouput voltages of the amplifiers are sent to the movable frames 341 and 342 which control the distributors 304 and 305 respectively of FIG. 5.

The electric circuits are therefore duplicated between the control stick 321 and the jack 310 of FIG. 5.

For the sake of simplicity, the damping voltages have not been represented in FIG. 6.

What I claim is:

1. In a hydro-electric servo control mechanism in which the final position of the principal hydraulic device is de fined by an input voltage, the output movement of the hydraulic device deriving a. feedback voltage, the combination comprising a torque motor having a rotor and normally responsive to the combined input and feedback voltages, an auxiliary valve distributor controlled by said torque motor, first electric means controlled by the output movement of said torque motor to provide an output voltage, an auxiliary hydraulic device controlled by said auxiliary valve distributor, second electric means controlled by the output movement of said auxiliary hydraulic device to provide a second output voltage, a principal valve distributor controlling said principal hydraulic device and controlled by said auxiliary hydraulic device, means for applying to the input of the torque motor the combined output voltages of said first and second electric means and the combined input and feedback voltages.

2. A servo control system comprising in combination, first hydraulic motor means having an output shaft and a control means, a second hydraulic motor means having an output shaft connected to the control means of said first hydraulic means and having a respective control means, an electric motor having an output shaft connected to the control means of said second hydraulic means, means connected to each recited motor shaft to derive a respective voltage corresponding to each shaft displacement, conducting means interconnecting each of the last recited means to a common summing junction, and conducting means connecting the summing junction to the input of said electrical motor to electrically balance the system.

3. In a hydro-electric servo-control mechanism in which the final position of the principal hydraulic device is defined by an input voltage, the output movement of the hydraulic device deriving a feedback voltage, the combination comprising two torque motors respectively normally responsive to the combined input and feedback voltages, each controlling an auxiliary valve distributor, first electric means controlled respectively by the output movements of said torque motors to derive respective first output voltages, two auxiliary hydraulic devices each having a movable shaft respectively controlled by the corresponding auxiliary valve distributor, said shafts being connected for translation, second electric means controlled by the output movement of said shafts to derive respective second output voltages, a principal valve distributor controlling said principal hydraulic device and controlled by the shafts of said auxiliary hydraulic devices, and means for applying to the inputs of the respective torque motors output voltages of the corresponding respective first and second electric means and the combined input and feedback voltages.

4. The system as set forth in claim 2, including a circuit interconnecting between said summing junction and a source of electrical input signals whereby an input signal unbalances the system and displaces the output shaft of the said first hydraulic motor means until cancellation of the signal at the summing point in re-establishing the condition of system electrical balance.

5. In the combination as set forth in claim '1, in which said torque motor has a rotor, said auxiliary distributor comprising a rotary valve, and means connecting said rotor and said rotary valve.

6. A servo-control system for controlling a movable member from an electrical input signal comprising in combination a source of input signals, a first hydraulic motor having an output shaft connected to said member and a control valve, a second hydraulic motor having an output shaft connected to the control valve of said first motor and having a respective control valve, a dynamo-electric device having an output shaft connected to the respective control valve of said second hydraulic motor, a potentiorneter for each recited motor and having each respective Wiper arm mechanically connected to the output shaft of its corresponding motor, conducting means electrically interconnecting each wiper arm to a common voltage summing point conducting means interconnecting the summing point with a control source of input signals, the system normally being electrically balanced when there is no input signal, and an amplifier having its input connected to the summing point and its output connected 15 to said dynamoelectric machine, whereby an input sig- 1131 from the control source unbalances the system and thereby displaces the movable member until cancellation of the signal at the summing point.

References Cited in the file of this patent UNITED STATES PATENTS 2,451,263 Webb Oct. 12, 1948 2,511,846 Halpert June 20, 1950 2,533,042 Polson et al. Dec. 5, 1950 2,655,939 Tauscher et al. Oct. 20, 1953 2,767,689 Moog Oct. 23, 1956 FOREIGN PATENTS 986,906 France Apr. 11', 1951 OTHER REFERENCES Bulletin of the Seismological Society of America, vol. 26, No. 3, July 1936 (pages 202 and 203). 

